Doctoral Defense in Medical Sciences - Hrafnhildur Gunnarsdóttir

On Monday, June 16, 2025, Hrafnhildur Gunnarsdóttir will defend her doctoral thesis in Medical Sciences at the Faculty of Medicine, University of Iceland.
The thesis is titled: A Nationwide Study on Primary Aldosteronism in Iceland: From Detection to Immunohistochemistry and Genetic Testing.

The opponents are Dr. Martin Reincke, Professor and Chief Physician at Ludwig-Maximilians University Hospital in Munich, and Dr. Marianne Aardal Grytas, Chief Physician at Haukeland University Hospital in Bergen.

The main supervisor was Dr. Helga Ágústa Sigurjónsdóttir, Clinical Professor, and the academic advisor was Dr. Ragnar Grímur Bjarnason, Professor. Also on the doctoral committee were Professor Emeritus Bjarni A. Agnarsson and Surgeon Guðjón Birgisson.

Professor Þórarinn Guðjónsson, Dean of the Faculty of Medicine, will chair the ceremony, which takes place in the Ceremonial Hall of the University of Iceland (Hátíðasalur) and begins at 9:00 a.m.

Abstract

Primary aldosteronism (PA) is the most common cause of secondary hypertension and results from excess aldosterone production in one or both adrenal glands. PA carries a higher risk of cardiovascular complications than essential hypertension. Underdiagnosis and diagnostic delay are associated with poorer outcomes.

The thesis aimed to assess the incidence of PA in Iceland, evaluate diagnostic procedures, and treatment outcomes, and explore the utility of immunohistochemistry (IHC) in guiding long-term follow-up. An evidence-based diagnostic protocol – including hormone testing, imaging, postural testing, and adrenal venous sampling – was applied, and histopathological reclassification using IHC was performed.

All adults diagnosed with PA in Iceland from 2007 to 2016 were included (n=58). Of these, 47% had unilateral disease and underwent surgery, while 53% had bilateral disease and received medical treatment. All patients presented with or developed hypokalaemia during the diagnostic work-up, highlighting the extent of underdiagnosis and diagnostic delay. Surgical patients showed greater reductions in blood pressure and medication use, indicating better treatment outcomes. IHC improved diagnostic accuracy and showed potential for tailoring long-term follow-up.

The findings underscore the need for increased awareness, broader screening, and simplified diagnostic pathways for PA.

About the doctoral candidate

Hrafnhildur Gunnarsdóttir was born in 1991 in Reykjavík. She graduated from the natural sciences program at Menntaskólinn í Reykjavík in 2011, earned a medical degree (cand. med.) from the University of Iceland in 2017, and completed her internship at Landspítali – The National University Hospital of Iceland the following year. Alongside her doctoral studies, Hrafnhildur has been training in internal medicine at Landspítali and has supervised undergraduate students.
Her parents are Hjördís Jóhannesdóttir and Gunnar Bergsveinsson. Hrafnhildur is married to Daníel Kristinn Hilmarsson, and together they have three daughters.